1. Field
This disclosure relates in general to wireless network systems and, more specifically, but not by way of limitation, to scanning for a suitable serving wireless access network with a mobile device.
2. Information
A mobile device can discover a wireless Access Point (AP) network station (e.g., access point, Femto cell, WiFi AP, Home Base Station) as part of periodic radio scanning for a suitable serving access network. Once an AP is discovered, it may be beneficial to the mobile device and the user to access the same AP at future times, provided the access is allowed, whenever the mobile device is again in the AP coverage area. For example, the mobile device may receive improved services (e.g. higher data throughput, better voice quality, lower signaling latency) when accessing a previously discovered AP and any associated network for the AP than when accessing some other network such as a public cellular network that provides wireless coverage in the same area. Furthermore, the user may be billed by the operator for the AP at a lower rate than by some other network operator with wireless coverage in the same area. In some cases, a user may even receive free wireless access from the operator of an AP (e.g. with the free access being an inducement or compensation to the user for entering and remaining within some specific area such as an airport, restaurant or shopping mall). In certain other cases, the operator of a cellular network may benefit in the form of reduced network loading and congestion by having a mobile device acquire certain APs whenever possible and thereby no longer need to directly access the operator's cellular network. However, re-acquiring an AP at a later time by the mobile device may be difficult and resource intensive. For example, the mobile device could perform a fast periodic scan when in the general vicinity of the AP, but this may consume battery power while the mobile device is outside the actual AP coverage area and may further interfere with support of other services for the user when accessing another wireless network since the mobile device may need to tune away from the current wireless network in order to perform a scan. The mobile device may conserve power and reduce the interference to other services by performing a scan at a lower rate, but this may delay re-acquisition once the mobile device enters the AP coverage area.
There is thus a need to improve the efficiency of AP acquisition and re-acquisition without substantially increasing latency. Currently, there are many ways to estimate a position of a mobile device on a network. For example, Global Navigation Satellite System (GNSS) chips on a mobile device can provide position estimates when the mobile device is located in outdoor and open space environments. In another example, Wide Area Networks (WAN) base stations and Access Point (AP) networks (e.g., using WiFi, CDMA, WCDMA, LTE or Bluetooth) can be used to estimate the position of a mobile device. Such position information can be used in combination with prior scan detection data to provide improved power conservation while scanning for an AP.